Forming die apparatus



A oct. zo, 1970 R H, HALL Em 3,534,573

FORMING DIE APPARATUS 2 Sheegts-Sheet l Filed April 26, 1968 ZN VENTE/RS Oct. 20, 1970 R. H. HALL ErAL 3,534,573

FORMING DIE APPARATUS Filed April 26, 1968 2 'sheets-sheet 2 United States Patent 3,534,573 FORMING DIE APPARATUS Robert H. Hall and Henry R. Tillman, Winston-Salem,

N.C., assignors to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Apr. 26, 1968, Ser. No. 724,354 Int. Cl. B21d 15/03 U.S. Cl. 72-62 3 Claims ABSTRACT OF THE DISCLOSURE A tubular piecepart is expanded in a conical die cavity rst by a rubber mandrel and then by a steel mandrel. A plunger forms one end of the die cavity and is movable for ejecting the piecepart from the die cavity a'fter each forming operation. A puller is provided at the other end of the die cavity for pulling the piecepart into the die cavity between forming operations.

BACKGROUND OF THE INVENTION Field of the invention The invention is concerned with the formation of tubular pieceparts. Such tubular parts may be used for example in waveguide sections. In order to insure the proper transmission of signals, waveguide sections must be accurately dimensioned. One such waveguide section takes the shape of a conical tubular piecepart which must have precise inside dimensions.

Description of the prior art In the prior art, electroforrning techniques were used to produce accurately dimensioned tubular pieceparts. Electroforming techniques are expensive and require considerable time. The prior art cold forming apparatus was incapable of producing the tubular pieceparts Within the required tolerances.

SUMMARY OF THE INVENTION An object of the present invention is a new and improved apparatus for cold forming precisely dimensioned tubular pieceparts.

In accordance with this and other objects of the invention, an apparatus for forming a tubular member to the desired inside and outside dimensions utilizes a tubular die member having a cavity with the desired outside dimensions for receiving a tubular blank. A movable plunger forms a rst end wall of the die cavity and is movable for ejecting the piecepart. A compliant medium, such as a rubber-like material, is rst injected into the center of the tubular blank to expand the tubular blank against the wall of the cavity. Then a non-deformable mandrel, such as a steel mandrel, having the desired inside dimension is inserted into the expanded tubular blank to form the blank to the desired inside and outside dimensions.

Another feature of the invention is the facilities for pulling the expanded tubular blank into the die cavity between forming operations.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of a tubular blank.

FIG. 2 is an isometric view of a conical-shaped piecepart l.formed from the blank of FIG. 1.

FIG. 3 is an elevation View of an apparatus for forming an intermediate conical-shaped piecepart from a tubular blank by inserting a high pressure uid medium into the tubular blank.

3,534,573 Patented Oct. 20, 1970 DETAILED DESCRIPTION Referring to FIG. 2, there is shown a tubular piecepart 10 such as a section of a waveguide transducer. Due to the desired electrical characteristics, the piecepart 10 is preferably copper. The piecepart 10 must be accurately formed having precise inside dimensions in order to insure that a signal being transmitted by a waveguide is properly handled. For example, referring to FIG. 5, the inside dimensions of the tubular piecepart 10 are formed to the outside dimensions of the mandrel 40. It is seen that the inside diameter of the piecepart 10 increases in steps which are irregularly spaced between the ends of the piecepart 10. In the prior art, it was necessary to form such a tubular piecepart 10 by using electroforrning techniques. The apparatus shown in FIGS. 3, 4 and 5 is used to cold forrn the piecepart 10 from a tubular blank 11. This results in a great saving in cost over the prior art method.

Referring now to FIG. 3, there is shown a base 12 upon which a die member 13 is mounted. The die member 13 has a cavity 16 extending from a iirst end 17 of the die member 13 to a second end 18 of the die member 13. The center portion of the die cavity 16 has a dimension conforming to the outside dimension of the piecepart 10. Referring to FIG. 5, it is seen that the dimensions of the cavity 16 are designed to correspond to the dimensions of the mandrel 40 taking into consideration the wall thickness off the piecepart 10.

Referring back to FIG. 3, a hydraulic cylinder 21 is mounted on the base 12 at the first end 17 of the die member 13 in line with an axis through the center of the cavity 16. The cylinder 21 has a piston rod 22 to which is attached a plunger 23 extending into the cavity 16. When the piston rod 22 is fully retracted, the plunger 23 forms one end wall of the cavity 16. After the piecepart lil has been formed, the cylinder 21 may be actuated to advance the plunger 23 and eject the piecepart 10 from the cavity 16.

An adapter 26 is designed to t into an enlarged portion of the die cavity 16 at the second end 18. A hydraulic cylinder 27 has a pin 28 attached to a piston rod 29 of the hydraulic cylinder for insertion into a detent 31 of the adapter 26 to secure the adapter 26 to the die member 13. A cylinder 33 is secured to the adapter 26 by suitable means such as mating threaded portions. The cylinder 33 is aligned with the axis through the center of the cavity 16.

A hydraulic cylinder 36 is mounted at the second end 18 of the die member 13 in line with the axis through the center of the cavity 16 and the cylinder 33. A plunger 37 is removably attached by a hinged connection 39 to a piston rod 38 of the cylinder 36 to extend into the cylinder 33. The hinged connection 39 allows the plunger 37, cylinder 33 and adapter 26 to be pivoted upwards to allow a tubular blank 11 to be placed in the die cavity 16. Also, the hinged connection 39 allows one end of a pliable rubber rod to be inserted into the blank 11 and the other end into the cylinder 33. When the plunger 37, cylinder 33 and adapter 26 are pivoted back and the adapter 26 secured to the die member 13 by member 28 i when actuated by cylinder 27 to lock member 31, the

hydraulic cylinder 36 may be actuated to advance the plunger 37 in the cylinder 33 to exert force on the rubber rod to expand the tu'bular blank 11 against the wall of the cavity 16. Other compliant mediums such as fluids, may be employed in the cylinder 33 in place of the pliable rubber rod. The rubber rod is convenient since it may be used many times and provisions need not be made for holding compliant mediums like liquids in the cylinder 33.

Referring now to FIG. 5, there is shown that a nondeformable mandrel l40 has been attached to the piston rod 38 in place of the plunger 37. Additionally, the hydraulic cylinder 27 has been deactuated and the adapter 26 and cylinder 33 have been removed. A ring 41 replaces the adapter 26 to form the wall of the die cavity 16 at the second end 18 0f the die member 13. The mandrel 40 has a dimension conforming to the precise inside dimensions desired of the piecepart 10. When the hydraulic cylinder 36 is actuated7 the mandrel 40 precisely forms the inside dimensions of the piecepart 10.

In actual operation, it is desirable to roughly form a number of intermediate pieceparts by inserting the compliant medium under high pressure through the cylinder 33 before changing the apparatus to use the steel mandrel 40'. Each of the intermediate pieceparts are ejected by the plunger 23 and the compliant medium or rubber removed from the intermediate piecepart. Consequently, when the steel memebr 40 is subsequently attached to the piston rod 38, the intermediate pieceparts must be pulled into the die cavity 16. Referring now to FIG. 4, two arms 44 and 45 mounted on the piston rod 22 are slidable within respective grooves on opopsite sides of the die member 13. The arms 44 and 45 have eyelets 46 and 47 formed in the ends of the respective arms adjacent the second end 18 of the die member 13 for receiving pins or bolts which attach a crossbar 50 to the arms 44 and 45. The crossbar 50 has a threaded member 51 extending along the axis through the center of the cavity 16 for engaging a block 42 fitted into the larger end of the intermediate conical piecepart. The threaded member 51 may be tightened to securely hold the intermediate piecepart between the block 52 and the plunger 23, When the hydraulic cylinder 21 is retracted, the arms 44, 4S and crossbar 50 move from right to left, as viewed in FIG. 4, to pull the intermediate piecepart into the die cavity 16. Holding the piecepart between the plunger 23 and the block 52 helps prevent bending of the edges of the piecepart as the piecepart is pulled into the cavity.

OPERATION Referring to FIG. 3, with the plunger 37, adapter 26 andthe cylinder 33 pivoted upwards about the hinge 39, a tubular blank 11 is inserted into the die cavity 16. One end of a resilient rubber rod is inserted into the tubular blank 11 and the other end of the rubber rod is inserted into the cylinder 33. The plunger 37, cylinder 33, and adapter 26 are pivoted back in line with the cavity 16 where the adapter 26 and the cylinder 33 are reinserted into the second end 18 of the die cavity 16 and secured by operation of the hydaulic cyline 27 inseting the pin 28 into the detent 31 of the adapter 26. The hydraulic cylinder 36 is actuated to advance the plunger 37 to develop a high pressure in the rubber in the center of the tubular blank 11. The force of the rubber inthe center of the tubular blank 11 expands the tubular blank 11 against the walls of the die cavity 16 to form an intermediate conical shaped piecepart which roughly has the dimensions of the piecepart 10 shown in FIG. 2.

After the tubular piecepart 10 has been roughly formed by the compliant medium under high pressure and the cylinder 36 retracted, the adapter 26 and cylinder 33 are detached from the die member 13 and the plunger 37, cylinder 33 and the adapter 26 are pivoted. upwards. The cylinder 21 is actuated to advance the plunger 23 to eject the piecepart from the die cavity 16. Other intermediate pieceparts may then be formed in the same manner as that described above.

The rubber is removed from the intermediate piecepart and the intermediate piecepart is reinserted into the die cavity 16. Due to the closeness of the t between the piecepart 10 and the walls of the cavity 16, the piecepart 10 can not be manually inserted to the full extent into the die cavity 16. Referring to FIG. 4, the crossbar 50 is attached to the eyelets 46 and 47 of the arms 44 and 45 and the block 52 is inserted in the larger end of the intermediate piecepart. The threaded member 51 is tightened to securely `grip the intermediate piecepart between the block 25 arid plunger 23. The hydraulic cylinder 21 is then retracted to pull the intermediate tubular piecepart into the die cavity 16.

The crossbar S is then removed and the steel mandrel 40 is attached to the piston rod 38 in place of the plunger 37. The hydraulic cylinder 36 is actuated to force the steel mandrel 40 into the cavity 16 to form an accurately dimensioned piecepart 10. After retraction of the mandrel 40, the piecepart is again ejected from the cavity 16 by the hydraulic cylinder 21 operating the plunger 23.

It is to be understood that the above-described embodiment is simply illustrative of the principles of the invention and that many other embodiments may be devised without departing from the scope and spirit of the invention.

What is claimed is:

1. An apparatus for forming a tubular piecepart to desired inside and outside dimensions, comprising:

a base;

a die member mounted on the base and having a cavity extending therethrough from a rst end to a second end of the die member for receiving the tubular piecepart, a central portion of the wall of the cavity having the desired outside dimensions of the piecepart;

a rst plunger;

iirst means mounted on the base for supporting the lirst plunger in the die cavity for advancement and retraction near the irst end of the die member, the iirst plunger, when retracted, forming an end wall in the cavity and wherein the tubular pieceparts may be ejected by advancement of the first plunger;

a cylinder which may be removably attached to the second end of the die member in alignment with the die cavity for receiving a compliant medium;

a second plunger;

second means mounted on the base near the second end of the die member and to which the second plunger may be removably atached for advancement and retraction relative to the die member, the second plunger when attached to the second means operable to force the compliant medium from the cylinder into the tubular piecepart to expand the tubular piecepart against the wall of the cavity; and

a non-deformable mandrel having the desired inside dimensions of the piecepart and which may be removably attached to the second means for movement into the piecepart to form the piecepart to the desired inside and outside dimensions.

2. An apparatus for forming a tubular piecepart to desired inside and outside dimensions as defined in claim 1, and which includes:

means for pulling the tubular piecepart into the die cavity at the second end of the die member.

3. An apparatus as defined in claim 1, and which includes:

a sliding arm attached to the first means and extending to the second end of the die member for advancement and retraction with the first plunger; and

clamping means mountable on the sliding arm at the second end of the die member for gripping the piecepart by its ends between the lirst plunger and clamp- 6 ing means to pull the piecepart into the die Cavity at 3,296,852 1/1967 Fuchs 72-370 the second end ofthe die member. 3,397,563 8/ 1968 Pelton 72-62 References Cited RICHARD J. HERBST, Primary Examiner UNITED STATES PATENTS 5 1,402,919 1/1922 Carlson 72470 U-S' C- X-R- 2,903,947 9/1959 Sands 72-62 72 370 

